How do you say goodbye?

For those that may not know I am in California right now for no other reason but to visit family and friends. Last night I visited with my Gram and Bappy (my dads parents) and I found myself unable to say goodbye. Bappy is not doing well, in fact he hasn't been doing well for a while but this is the worst he has ever been and there is no hope of improvement. We know this and he knows this and because we all know, he is embarrassed. In our usual tradition I was supposed to stay the night with them but found myself driving home at 8pm to keep him from getting agitated that I was there for so long. He refuses to go to the doctor even though his conditions is growing rapidly worse. He refuses to have company over, friends that he has known forever are being turned away at the door and their gifts going unnoticed. Because I didn't stay the night I am going back on Thursday to make them dinner, which brings up my question...how am I going to say goodbye? It was easy last night because I told them I would see them Thursday but I will be going home next week and then what? In all likelihood this will be my last opportunity to spend time with him and I would be perfectly content with just sitting with him in silence holding his hand, but will he let me?